Reduction of Flicker Noise in AlGaN/GaN-Based HFETs After High Electric-Field Stress

We report on the evolution of AlGaN/GaN-based heterojunction field-effect transistor (HFET) operation under high-electric-field stress. Specifically, a 10 ~ 15 dB decrease in the flicker noise is observed after stress in contrast with what has been nominally observed and reported in the literature in the realm of direct-current characteristics. Gate lag measurements revealed a trap state with an activation energy of 0.20 eV in the pristine devices, which manifests itself as a generation-recombination peak in the flicker noise spectrum. This trap state becomes undetectable in gate lag and noise measurements after high-field stress. Analysis shows that the phenomena observed are consistent with the change of surface charge profile during high-electric-field stress.